# How To Use An Abacus

## Reading Numbers on the Abacus

The decimal number system is represented on the abacus using beads and columns. Each column displays a digit between 0 and 9 (depending on the bead combination). The single top bead has a value of 5 and the four bottom beads have a value of 1 each. The abacus has a 1's column, a 10's column to its left, a 100's column and so on. In the image below, the abacus is showing the number 17,539.

## Small Friend and Big Friend Concepts

When a number has a small friend or a big friend, it is just a fun way of describing its complementary number. Each number 0 to 5 has a small friend number and when they are summed together they equal 5. For example, the small friend of 2 is 3 because they sum to make 5. Similarly, each number, 0 to 10, has a big friend number and when they sum together they make 10. Here are some examples: 1's big friend is 9, 4's big friend is 6 and 0's big friend is 10. A solid understanding of these basic math concepts is required to progress in abacus.

## Direct Movements on the Abacus

A direct movement is the most simple abacus action as it occurs when neither the small friend or big friend value are required for the calculation. The example below demonstrates the direct movements needed for summing 5 and 3 on the abacus. First, the top bead, with a value of 5, is pulled down to show number 5. Then three bottom beads, with a value of 1 each, are pulled up to give the answer 8. Direct movements can be practiced in Part 1: Sum to Nine on the Abacus where students learn to add and subtract on the abacus.